18 MATHILDE M. LANGE 
it as primary blastema. As this blastema does not degenerate, 
it is used to supply the material for some regenerating tissue. 
It is not likely that the primary blastema contributes any ma- 
terial for the construction of the nerves or muscles, for the nuclei 
of the primary and second blastema differ greatly in structure. 
The nuclei of the former are generally elongated and provided 
with several nucleoli, the nuclei of the latter are larger in size, 
round in shape, only have one nucleolus, and show a greater 
affinity for staining agents. All these differences indicate that 
it is quite impossible for the nerves or muscles to draw any 
material for their regeneration from the primary blastema. 
However, it is very likely that the primary blastema contributes 
a great part of its material to the construction of the new con- 
nective tissue, especially the dermal layer. There are two facts 
which further strengthen this theory. First, the similarity of 
the nuclear structure and, secondly, the fact thaf the primary 
blastema is dislocated by the second blastema’s being pushed 
sideward, so that it gradually occupies the place of the dermal 
connective tissue. Most of the papers dealing with the subject 
of regeneration do not definitely state what ultimately becomes 
of. the cicatricial tissue. This applies to the three papers here- 
tofore written on the regeneration in Mollusca. Nusbaum and 
Cucagna (’15) mention the presence of connective-tissue cells 
in the cicatricial tissue before the same is covered with epithelium, 
but they do not mention the origin of these cells. Even though 
the literature treating of regeneration in worms is very volumi- 
nous, I was not able to find very much information on the further 
utilization of the cicatricial tissue. Many authors never even 
mention its presence. Others explain its formation, but do not 
say what becomes of it later. Friedlander intimates that muscle 
fibers might arise from the cicatricial tissue, but does not state 
this as an actual fact. Rievel, who believes that the cicatricial 
tissue (he calls it granulation tissue) has its origin in the meso- 
derm, claims that later it becomes mesenchymatous and finally 
forms the unstriated muscles. According to Hescheler, the 
cicatricial tissue becomes fibrous (in the course of regeneration) 
and arranged in layers which run parallel to the front external 
